In recent years, the number of patients suffering from respiratory system diseases such as asthma, pulmonary emphysema, chronic bronchitis and the like has tended to increase. One of the most effective therapeutic methods for these diseases is oxygen inhalation therapy. Such oxygen inhalation therapy is that oxygen gas or oxygen-enriched air is inhaled to patients. An oxygen enrichment device separating oxygen from the air, an oxygen supply device using liquid oxygen or oxygen gas cylinder, and the like are known as an oxygen supply source used for oxygen inhalation therapy. However, an oxygen enrichment device is mainly used for home oxygen therapy because it is convenient to use and easy for maintenance and management.
An oxygen enrichment device is a device to supply oxygen by separating and concentrating oxygen that makes up 21% of the air. As such device, there are a membrane-type oxygen enrichment device that uses an oxygen enrichment membrane which selectively permeate oxygen and a pressure swing adsorption-type oxygen enrichment device that uses an adsorbent which selectively adsorbs nitrogen or oxygen. A pressure swing adsorption-type oxygen enrichment device is mainly used because of a benefit of obtaining high oxygen concentration of 90% or more.
The pressure swing adsorption-type oxygen enrichment device continuously produces a highly concentrated oxygen gas by repeating an adsorption step and a desorption step. In the adsorption step in which un-adsorbed oxygen-enriched gas is obtained, nitrogen is adsorbed under pressurized conditions on an adsorbent which selectively adsorbs nitrogen relative to oxygen such as 5A, 13X, Li-X type molecular sieve zeolites filled in an adsorption cylinder to which compressed air is supplied by a compressor. In the desorption step in which the adsorbent is regenerated, nitrogen adsorbed on the adsorbent is desorbed by reducing the pressure in the adsorption cylinder to atmospheric pressure or less by evacuation.